Exemplary embodiments of the present invention relate to aircraft technology. In particular, exemplary embodiments of the present invention relate to actuator technology for aerodynamically effective elements of an aircraft. Furthermore, exemplary embodiments of the present invention relate, in particular, to a pneumatic decoupling device, an actuator element, an actuator assembly, as well as an aircraft, in particular, an airplane or a helicopter.
Actuators are used in aircrafts, in order to move elements of the aircraft by mechanical means and to change the elements in their position or orientation. In airplanes these elements are, for example, the rudders or elements of the wings, in order to influence the upward lift characteristic of the airplanes. In helicopters these elements can influence, for example, the varying angle of pitch of the rotor blade by means of a swash plate.
Such actuators are typically designed as hydraulic elements, because to date it has been possible to master this technology and because this technology is less subject to faults. When a fault occurs, conventional hydraulic actuators can still be moved in most cases. In other words, they do not block when a fault occurs.
The increasing electrification of the aircraft has made it desirable to replace hydraulic actuators, which in some cases might require that the hydraulic system run throughout the entire aircraft, with electric actuators. These electric actuators can be powered strictly electrically, whereby such electric connections are usually easier to install in an aircraft than, for example, hydraulic lines. At this point a movement generated by such an electric actuator can also be implemented strictly electrically, for example, with the help of a suitable drive by means of an electric motor; a local hydraulic system can also be provided at the actuator, in particular, a hydraulic system, which is disposed in the actuator system and which also has only to be supplied with electric energy from the outside.
FIG. 1a shows a schematic drawing of an electromechanical actuator.
For example, two motor elements 1 are attached to the drive unit 8 of the actuator element 3 by means of the use of a suitable attachment, consisting of a motor shaft 2a and a suitable transmission 2b. The drive unit 8 is variable in its length l, in particular, in its distance between the two attachment points 5a, b, so that a variation in the length of the drive unit 8 of the actuator element 3 changes the distance between the attachment points 5a, b. By suitably clamping between the elements this approach makes it possible, for example, to move or tilt an aerodynamically effective structure. The drive unit 8 consists of a first drive element 8a and a second drive element 8b, constructed, for example, as a ball screw 8 with a spindle nut 8b and a drive spindle 8a. When the drive spindle 8a is rotated, the spindle nut 8b can be pushed onto the drive spindle, so that the rotation of the drive spindle 8a provides a change in the length of the drive unit 8 and, as a result, a change in the length of the actuator element 3 or more specifically a change in the distance between the attachment points 5a, b. In the event that an actuator element is defective, in particular, in the event that mission-critical, aerodynamically effective surfaces are defective, it has to be ensured that, despite the defect, they can at least still be moved. In the case that an actuator element fails, a certain degree of redundancy is provided as a function of the specific application. In the case of tails or rudders, it is possible, for example, to arrange a second actuator element in a force parallel manner relative to the first actuator element, so that the change in the position or orientation of the aerodynamically effective surface can be perceived by one of the two actuator elements or also by both actuator elements together. If at this point one of the two parallel actuator elements fails, then the other actuator element can at least maintain the function. However, even more relevant in this context are the defects of the actuator elements that no longer allow, therefore, a length variation to be carried out. For example, the rupture of a ball of the ball screw might block the drive spindle and the spindle nut in relation to each other, so that it is no longer possible to change the length of the actuator element. In such a case the actuator element that is arranged in parallel can no longer perform a control function of the aerodynamically effective surface. In the worst case scenario it would no longer be possible to control the airplane; and, as a result, the airplane might crash.
In order to continue to keep the electromechanical actuator element variable in its length, even when a fault occurs, decoupling devices or more specifically decoupling mechanisms can be integrated into the actuator elements. When a fault occurs, the decoupling devices enable such a decoupling, in order to be able to continue to generate a suitable force, at least by supplying a force from the outside, for example, by means of an actuator element that is arranged in a force parallel manner, in order to keep the aerodynamically effective surfaces in operation, while at the same time the defective actuator element is changed in its length by means of the force from the outside and, as a result, does not block the movement of the aerodynamically effective surface.
FIG. 1b shows an exemplary embodiment of such an actuator element. In the final analysis the only distinction between the embodiment from FIG. 1b and that of FIG. 1a is the provision of a decoupling device 10. In this case the decoupling device 10 does not merely decouple the two drive elements 8a, b from each other, but rather a decoupling process is performed in such a way that the engagement points 5a, b are decoupled. In this respect one of the engagement points is more or less connected to both drive elements of the drive unit even in the decoupled state, while the connection of a drive element to the second engagement point 5b is released. As a result, the length of the actuator element can be changed, independently of whether a mechanism of the drive unit, for example, the first drive element 8a to the second drive element 8b, is blocked.
One aspect of the present invention is directed to a decoupling device for an actuator element.
According to a first embodiment of the present invention, a pneumatic decoupling device is provided for an electromechanical actuator element, the pneumatic decoupling device comprising at least one pressure accumulator element with at least one outlet and at least one tripping mechanism, configured to release the pressure, stored in the pressure accumulator element, in a controlled fashion. The outlet of the pressure accumulator element can be coupled to an electromechanical actuator element, so that, when the tripping mechanism is tripped, the pressure, stored in the pressure accumulator element, can be released to the mechanical actuator element, in order to trigger a decoupling function in the electromechanical actuator element.
An additional embodiment of the present invention discloses an actuator element, comprising a drive unit with a first drive element and a second drive element, wherein the first drive element and the second drive element interact operationally in such a way that they effect a variation in the length of the actuator element. Furthermore, the actuator element has a decoupling mechanism, which operationally decouples the actuator element, so that the variation in the length of the actuator element is made possible, independently of the drive unit, in particular, without operationally decoupling the first drive element and the second drive element. Furthermore, the actuator element comprises, according to the present invention, a decoupling device, operationally coupled to the decoupling mechanism and configured to make the stored pressure available to the decoupling mechanism, so that when the pressure is provided, the decoupling mechanism operationally decouples the actuator element.
Another embodiment of the present invention discloses an actuator assembly, comprising at least two actuator elements according to the present invention, wherein the at least two actuator elements are arranged in a force parallel manner, so that a variation in the length of the actuator assembly can be effected by one actuator element alone or by both actuator elements in parallel; and wherein one decoupling device, according to the present invention, is attached to the actuator elements.
An additional embodiment of the present invention discloses an aircraft, in particular, an airplane or a helicopter, comprising an actuator assembly, according to the present invention, and/or an actuator element, according to the present invention.
One aspect of the present invention is the provision of a decoupling device for an electromechanical actuator element, which works based on a pneumatic principle. In other words, the decoupling device, according to the invention, comprises a pressure accumulator element, in the interior of which gas having a positive pressure is stored, and, as a result, the pressure accumulator element is configured to release this pressure to other elements through expansion of the gas, for example, in the directed outflow by means of the use of an outlet. If in the context of the present invention the topic under discussion is a pressure release and/or a stored pressure, these two concepts may be construed as the force released by the compressed gas due to its positive pressure.
In this respect the stored pressure in the decoupling device is released to an electromechanical actuator, which is configured to carry out a decoupling of its drive elements, as a result of the pressure it has received, in particular, a decoupling of the attachment points of the actuator element, wherein in the end their distance represents the effective length of the actuator element for adjusting the aerodynamic effective surfaces in an aircraft. However, ultimately the decoupling device, according to the invention, is separated from a concrete implementation of an actuator element, as long as the actuator element is configured to carry out the decoupling as a result of the pressure it has received. In this case even the specific embodiment of the decoupling device is defined in essence only by the fact that it provides a suitable pressure accumulator element, which in turn can release in a controlled fashion the stored pressure by means of a suitable tripping mechanism, when a fault occurs and/or when the electromechanical actuator is decoupled. The effect and, thus, the decoupling in the actuator element as a result of the stored pressure is hereinafter a functionality that is to be represented by the actuator element itself.
A preferred embodiment of the present invention can provide a pressure determining device for determining the pressure in the pressure accumulator element. In this case the pressure determining device may be designed as a device from the group, consisting of a visual pressure determining device, a mechanical pressure determining device, an electronic pressure determining device and/or a pressure sensor disposed in the pressure accumulator element.
In order to check the flawless function of the pneumatic decoupling device, it is relevant for this purpose to be able to determine in essence that the pressure, which is stored or more specifically present in the pressure accumulator element, is sufficient for tripping an actuator element. As a result, it is preferred that a pressure determining device for determining the pressure in the pressure accumulator element be provided. Such a pressure determining device can be designed, for example, as a visual pressure determining device, for example, a spring element in the wall of the pressure accumulator element, which is forced outwards as a result of the pressure prevailing in the pressure accumulator element, and which has a visual indicator. It is also possible to provide a mechanical pressure determining device, in which, for example, the above described spring element is inserted, moved, and/or pressed into the pressure accumulator element by hand, for example, by a service technician, on site. This spring element in turn assumes that there is sufficient pressure in the pressure accumulator element to move the spring elements outwards as a result of the positive pressure. It is also conceivable to provide an electronic pressure determining device, as such a pressure sensor, that is disposed in the pressure accumulator element.
According to an additional preferred embodiment of the present invention, the pressure accumulator element may have at least two outlets, wherein an electromechanical actuator element can be connected to each of the at least two outlets; and wherein the tripping mechanism is designed to release the stored pressure to an electromechanical actuator element by means of the use of one of the at least two outlets, wherein, following release of the stored pressure to an electromechanical actuator element, the decoupling function of the second electromechanical actuator element can no longer be triggered by means of the decoupling device.
As described above, the actuator assemblies are provided for flight-relevant, aerodynamically effective surfaces, so that, when an actuator element is defective, the function of adjusting the aerodynamically effective surface is taken over by the second actuator element, which is arranged in a force parallel or more specifically action parallel manner; and, thus, the functionality or more specifically the airworthiness of the aircraft can be maintained. If, however, a fault should occur with the effect that a decoupling device of an actuator element decouples (simultaneously) both actuator elements of an actuator assembly, then this event would also mean the loss of the ability to control the aerodynamically effective surface and, thus, possibly the entire aircraft.
For this reason it is preferred to provide a decoupling device, which supplies, for example, two actuator elements, which are arranged in a force parallel manner, jointly with a decoupling functionality. In this case the decoupling device is configured to provide exclusively one of the two actuator elements with a functionality that can be used for decoupling the actuator element or more specifically for tripping the decoupling mechanism of the corresponding actuator element. Therefore, based specifically on the case of a pneumatic decoupling device with a pressure accumulator element, a pressure accumulator element can be connected to the decoupling mechanisms of two actuator elements, which are arranged in a force parallel manner. In this context the pressure accumulator element stores only an amount of pressure that is required to decouple one of the two actuator elements. In other words, when the pressure accumulator element has released pressure to an actuator element for decoupling, the pressure accumulator element can no longer have enough pressure to decouple, in addition, the second actuator element that is arranged in a force parallel manner. This arrangement significantly augments the safety during the normal operating mode, because both actuator elements cannot be decoupled by mistake. In another possible embodiment a suitable outlet port in the decoupling mechanism is opened by actuating the decoupling mechanism, so that, upon exercising the decoupling function, the pressure, which has remained in the pressure accumulator element, can escape through the outlet port in the decoupling mechanism. This approach makes it possible to improve the safety, because the second actuator element cannot also be decoupled by mistake.
According to an additional preferred embodiment of the present invention, the tripping mechanism may be designed as a single tripping mechanism, configured to release the pressure selectively by means of each of the at least two outlets; or the tripping mechanism may be designed as a multiple tripping mechanism, wherein each of the outlets is assigned a tripping mechanism of the multiple tripping mechanism. In other words, a multiple tripping mechanism comprises parallel or more specifically redundant tripping mechanisms.
As a result, such an approach ensures, in particular, that of the two force-parallel actuator elements only one actuator element can be decoupled. In the case of a single tripping mechanism, it can be designed in such a way that it releases or more specifically opens either one or the other outlet of the pressure accumulator element and, as a result, releases the stored pressure to the decoupling mechanism of an actuator element. In the case of a multiple tripping mechanism, each tripping mechanism can be controlled separately. In the event that one tripping mechanism was already tripped, then the other can be made functional by electronic means or by other suitable measures. Both measures can ensure that only one of the two force-parallel actuator elements of an actuator assembly can be decoupled, in particular, no simultaneous decoupling of both actuator elements that are arranged in a force parallel manner.
According to another preferred embodiment of the present invention, the tripping mechanism may be designed as a positive locking element with a first force element, a second force element and a drive element, wherein the first force element is configured to hold a positive engagement of the positive locking element; wherein the drive element is configured to release the positive engagement against the action of the force of the first force element; and wherein, when the positive engagement is released, the second force element is configured to release the pressure, stored in the pressure accumulator element, by means of the outlet. In particular, the direction of force of the first force element and the second force element may not be oriented parallel or in essence perpendicular to each other.
Such an embodiment or more specifically arrangement offers the advantage that the positive engagement of the positive locking element can be held more or less force neutral and, in particular, does not have to be held against the direction of force of the second force element. This approach can ensure, in particular, that, when the positive engagement is closed, there is no need to generate a counter-force that, when a fault occurs in the event of an absence of this force, would result in a more or less automatic and undesired triggering of the release of the pressure from the pressure accumulator element. In addition, the forces of the first and second force element can be significantly different. The first force element can hold only the positive engagement, whereas the second force element can generate a force, in order to release the pressure, stored in the pressure accumulator element. It is also possible, for example, that the force of the drive element that is required to release the positive engagement may turn out to be comparatively small and, in particular, may be independent of the action of the force of the second force element to release or rather to output the stored pressure. While, for example, the first force element can be a comparatively small spring force element in order to hold the positive locking element in a recess, the second force element can be a comparatively strong spring force element in order to trip the tripping mechanism.
According to an additional preferred embodiment of the present invention, the pressure in the pressure accumulator element can be held by means of a sealing effect of a sealing element, which is arranged in the at least one outlet. In this case the tripping mechanism can be configured to cancel, in particular, to irreversibly cancel, the sealing effect, and, thereby, for example, to destroy or to damage the sealing element, so that its sealing effect can no longer be maintained to its full extent. In particular, the second force element can be designed to exert a force on the sealing element, so that the sealing effect is cancelled; and the pressure, stored in the pressure accumulator element, is released by means of the outlet.
Such a sealing element can be, for example, the provision of a diaphragm element, which is made, for example, of a suitable plastic material or metal, which is punctured by means of the tripping mechanism, in particular, with the use of the force provided by the second force element. Thus, the tripping mechanism can at least partially destroy the sealing element, so that a pressure connection between the outlet and the pressure accumulator element is established, as a result of which the pressure, stored in the pressure accumulator element, can be released to an actuator element by means of the use of the outlet.
According to another preferred embodiment, the actuator element may have two attachment points exhibiting a distance that can be determined by changing the length of the actuator element. In this case one of the drive elements can be connected in a more or less operatively direct manner to one of the attachment points; and wherein the decoupling mechanism is connected in a more or less operatively direct manner to the other one of the attachment points; and wherein in the coupled state of the decoupling mechanism, the distance between the two attachment points, thus the effective length of the actuator element, can be adjusted by means of the actuator element, in particular, its drive unit; and wherein in the decoupled state of the decoupling device the distance between the two attachment points can be changed by applying a force to the attachment points from the outside.
As a result, an actuator element, according to the invention, knows two different operating modes. In this case one operating mode shall be treated as equal to a conventional normal operation, in which the actuator element has a drive unit, which can effect, suitably actuated, a variation in the length of the actuator element. As a result of this option of a controlled variation of the length, it is possible to use the actuator element to influence in a targeted way the position and/or orientation of an aerodynamically effective surface of an aircraft. In the second state, in the decoupled state, the actuator element is no longer capable of providing by itself its length variation function, at least not to the full extent, due to, for example, a defect of the drive unit. In the decoupled state it is now ensured that the variation in the length of an actuator element, arranged in a force parallel manner, is not blocked or rather suppressed by the defective actuator element. Due to the decoupling mechanism the drive unit is now decoupled in such a way that a variation in the length of the decoupled actuator element can be carried out by tension or pressure on the attachment points. In this respect it is preferred that the first drive element and the second drive element be not simply decoupled, because when a fault occurs, as a result of which the first drive element and the second drive element are mutually blocked, such a decoupling might not be feasible.
According to an additional preferred embodiment of the present invention, the drive unit can be designed as a ball screw, wherein the first drive element and the second drive element can be designed as a drive spindle and a spindle nut of the ball screw.
In this case a ball screw can be a preferred option to effect the variation in the length of an actuator element, while a drive unit, which is designed in this way, has sufficient stability and can transmit an appropriately large force.
Another preferred embodiment of the present invention discloses an actuator assembly, wherein in the case of a defect of a drive unit of an actuator element, the decoupling device trips the decoupling mechanism of this actuator element, so that the actuator element is operationally decoupled, while the variation in the length of the actuator assembly can still be effected by the non-decoupled actuator element.
In other words, two actuator elements, which are arranged in a force parallel or rather action parallel manner, are provided, for example, in the actuator assembly. In the case of a defect of an actuator element, this actuator element can be decoupled by means of the use of the decoupling device, so that then the length of this actuator can be changed by a force, which is provided from externally, in particular, at its attachment points. This external force can be generated, for example, by the second actuator element, which is arranged in a force parallel or rather action parallel manner. As a result, this second actuator element can adjust the position of an aerodynamically effective surface and, in so doing, can simultaneously extend or shorten the decoupled actuator element analogous to its own length.